Anti-splat cowl flaps popping fuses

I?ve had a couple of fuses blow in the cowl flaps. It happened today at 9kft when I went to close them. I pulled the fuse and put a new one in. The label on the wire was a 1 amp fuse. I had a 3 and stuck it in there and it popped immediately.

I quit sticking fuses in after that. I realized after the fact that the switch was in the closed position when I replaced the fuse and the flaps were obviously still open. I stuck a 5 amp fuse in once back on the ground (with the switch in the open position) and cycled them a few times and it was all good. I don?t feel comfortable with a 5 amp fuse in there where a 1 amp fuse should be.

Any ideas on why I would be popping fuses?

May be binding

Check to see if the flap is rubbing or binding while trying to extend or retract, that might overload the motor, and cause a spike in current?

Steve

sibriggs said:

Check to see if the flap is rubbing or binding while trying to extend or retract, that might overload the motor, and cause a spike in current?

Steve

Click to expand...

Ditto this. My first cowl flap came with signficant binding that I didn't realize mattered. After repeated blown fuses and even some attempts to file out the binding I contacted Alan at AntiSplat and he promptly replaced the cowl flap. That solved the problem.

I've found that my cowl flap doesn't like airspeed over about 105-110 KIAS, there is too much air load on it for opening. Closing doesn't seem to be an issue. If you can put an ammeter in the circuit and check the actual loads in flight at various airspeeds you'll have the full story.

I pulled the cowl today and immediately found the issue. The wires between the cowl flaps was taped with foil tape to the lower cowl. That tape had peeled back a bit too close to the exhaust. The insulation had melted and the wires were touching.

I managed to break one of the tiny wires off AT the actuator with nothing sticking out, so I guess I?ll need to order another actuator.

The bigger issue was that there was a good amount of oil on the bottom cowl that appeared to be coming from somewhere around the #1 cyl. On the starter, alternator, and cowl up in the front corner. This engine has never leaked like that and it is down about a quart over the last 2 hr flight.

Knowing that my flaps were open on my way back I took a very shallow decent with power left in to keep the cht?s in the 325-330 range all the way until short final so I don?t think I had a shock cooling issue.

I?m going to replace the actuator and do a runup after cleaning everything to see if I can tell where the oil is coming from.

It is standard convention in the higher levels of aviation to never reset a popped CB in flight. Same with swapping a fuse. This being a good example of why not.

As someone once asked, "would you rather be flying in a glider,or a Roman Candle?"

Troubleshoot blown fuses and CB's on the ground.